All you have to do is make sure your gas cap is on tight and unhook the negative terminal from your battery and wait a couple of minutes. Then reattach the cable and it should take care of the problem.

If this doesn't do the trick, check the hoses on the charcoal canister, it's in the back just in front of the fuel tank.

If the hoses and connections seem sound you may need a new purge solenoid.